I like my little map-cue sheet holder I got from Adventure cycling about 12 years ago for $10. It velcros to my handle bar, is waterproof and has performed well in the nearly 100,000 miles in all kinds of weather it's been.
It's still $10 at www.adventurecycling.org
Adventure Cycling Map Case
Adventure Cycling Map Case
Product ID: BT-225
A perfect fit for Adventure Cycling's national route maps. L&C map panels are smaller so they are not a perfect fit.
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Price: $10.00